Engineering Covalent Organic Frameworks towards Enhanced Crystallinity, Mechanical Resilience, and Photochemical Applications

Mohata, Shibani (2025) Engineering Covalent Organic Frameworks towards Enhanced Crystallinity, Mechanical Resilience, and Photochemical Applications. PhD thesis, Indian Institute of Science Education and Research Kolkata.

Text (PhD thesis of Shibani Mohata (17IP019)) 17IP019.pdf - Submitted Version Restricted to Repository staff only Download (25MB)

Abstract

Colossal interest in Photocatalytic reduction of CO₂ is bestowed to the potential of generating chemical fuels while addressing the rising levels of CO₂. In this regard, porous materials have come to the forefront owing to their molecular-level precision in structural and chemical tunability. Although significant efforts have been made, specific challenges remain unaddressed. It is essential to design materials with high crystallinity, porosity, and stability to improve their performance and use them for several cycles without degrading the material. Hence, efforts must be made to improve the crystallinity while maintaining the stability. Furthermore, the processability of the material is another challenge. It is well known that more processable forms of materials like films are necessary regarding practical applications. Also, they need to be grown on various substrates for a plethora of applications. This makes it crucial to understand the interaction between COF and substrates to design multifunctional materials. Finally, while using these materials for photocatalysis, certain challenges remain like the rampant use of metals, sacrificial agents, parasitic HER in water, and organic solvents. Hence, in this work, we have focussed on three critical aspects: a) design, b) property, and C) application. We have designed a strategy to enhance the crystallinity of the -keto-enamine-linked COFs while maintaining their stability. Subsequently, we have developed an interfacial layer grafting methodology to fabricate Janus-type COF-graphene thin films and studied the morphological dependence on the final mechanical properties. Finally, we have used the principles of reticular chemistry to design porous nanostructures with internal molecular free volume for metal-free, selective photocatalytic CO₂ reduction in water.

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